The present invention relates to a trailer landing gear, lifting gear, dolly, or the like, drive units, gear boxes, rotary motors, improved trailers, drive adapters, and landing gear systems, components and methods. More particularly, the present invention is directed to an improved trailer landing gear apparatus and method including a shaft and gear assembly adapted to be attached to a drive shaft of a landing gear and driven by a rotary motor or a hand crank.
A conventional trailer landing gear, lifting gear, dolly, or the like, includes a pair of spaced landing gear legs and feet which extend downwardly from the floor of the trailer and are operatively attached to screw and follower or a rack and pinion gear arrangement driven by a landing gear drive shaft which extends between the legs and which causes extension or retraction of the legs and feet depending on the direction in which it is rotated. Typically, a hand crank handle is attached to the landing gear drive shaft by a pin or bolt which serves as a hinge connection allowing the handle to be pivoted out of the way while not in use. Manual rotation of the handle in one direction causes extension of the feet and lifting of the trailer to, for example, separate the trailer from a semi-tractor, and requires considerable time and effort on the part of the person manually rotating the hand crank.
Attempts have been made to reduce the effort required to manually operate the crank handle, for example, a two-speed gear box has been added to the landing gear to allow the hand crank handle to be attached to either a high speed or low speed input shaft of the gear box.
Further, power-operated actuators have been provided to rotate the landing gear drive shaft in either direction in order to extend or retract the landing gear feet automatically rather than manually. Such power-operated actuators are described for example in U.S. Pat. Nos. 4,345,779, 4,400,986, 4,402,526, 5,050,845, and 5,299,829.
U.S. Pat. No. 4,345,779 discloses a drive mechanism for a vehicle trailer lifting gear including a rotary drive unit driven by air under pressure supplied from the vehicle and having a drive socket engaging a nut welded to a shaft of the trailer lifting gear assembly. U.S. Pat. Nos. 4,400,986 and 4,402,526 disclose a landing gear actuator adapted to be connected to the crank shaft of the landing gear of a semi-trailer. The crank shaft is rotated by gears and ratchets which are driven by pawls reciprocated by an air actuated cylinder unit.
U.S. Pat. No. 5,050,845 discloses a pneumatic lift system for raising and lowering the landing gear of a trailer including a pneumatic motor supported by the landing gear. A gear shaft spline assembly is provided between the speed reducer that is coupled to the pneumatic motor and the crankshaft that drives the landing gear high-low gear reduction assembly. The spline assembly permits the crankshaft to axially translate and shift gear arrangements in the gear reduction assembly without separating the crankshaft from the pneumatic drive.
U.S. Pat. No. 5,050,845 mentions other pneumatic drives used to operate landing gear for trailers and which include air motor drives which drive a transmission that in turn drives the existing conventional landing gear shaft. Pressurized air is taken from the existing brake line to drive the motor. A valve is positioned between the brake line and the motor to control the rotational direction of the motor as well as to turn the motor on and off. Generally these pneumatic systems have been designed to be mounted to the undercarriage of the trailer body. While these designs permit the pneumatic system to be mounted to a flat bed type trailer, they are not suitable for mounting to trailers not having a flat bed, such as trailers having a cylindrical body or tank.
U.S. Pat. No. 5,299,829 appears to disclose one of the pneumatic systems for automatic operation of the semi-trailer landing gear as described in U.S. Pat. No. 5,050,845.
Examples of hydraulic, pneumatic, or hydro-pneumatic cylinder type trailer lifting systems are described in U.S. Pat. Nos. 3,177,664, 4,993,688, 5,100,105, and 5,401,046.
The above described power actuators or hydraulic and pneumatic lift systems suffer from the drawbacks of being overly complicated, expensive, difficult to use, lack versatility in placement, do not provide for manual as well as automatic raising or lowering of the landing gear, are not portable or adapted for easy attachment or detachment from conventional landing gear drive shafts, and/or the like.
Hence, there exists a need for an improved trailer apparatus, landing gear, lifting gear, dolly, or the like, drive unit, gear box, rotary motor, trailer, drive adapter, system, component and/or methods.